If the zone is only three heads, it wouldn't cost a fortune just to replace them, assuming you haven't yet done that. And do get the pressure gauge and take some readings. The too-high/too-low pressure readings on the upstream side of the zone valves will help narrow down zone problems for anyone without professional repair experience.

Lars, that is actually what I going to investigate now. I am waiting on the city to come out and check the check valve on the system. I have asked around, and apparently they are going bad around town at a more than normal rate.

Mrfixit, they are 3 rainbird model 3500 sprinklers in the zone. I have 3 of those same sprinklers on 2 other zones on my system that work flawlessly. I have changed the type and number of sprinklers in the zone with the same results and the same "fix".

Wet Boots, I have been switching and temporary plugging the sprinklers with the same results. I used my pressure gauge and the pressure is consistent regardless of zone used.

Thanks everyone for giving me suggestions and helping me out with this. I am waiting for the city to show up and see about the check valve...I really hope they show up soon and that is the fix.

Are the sprinklers attached to ells? like marlex ells or street ells?
Maybe there's debris in the line or ells.
Maybe the springs in those sprinklers are too strong. Try some PGJ's or sprinklers without checks.

This post has been edited 1 times, last edit by "mrfixit" (Mar 2nd 2018, 5:13am)

There may be a pressure regulating valve in the pathway of the water leading to the system, and that will give readings that differ from those systems with unregulated supplies.

Besides a pressure gauge, there is the water meter itself as a measuring device. Many of them today have digital readouts that will show you the precise flow in a zone. Should there be a blockage between the zone valve and the heads, the flow will be less than for the same heads on a working zone.

Wet Boots for the win. Thanks to everyone who helped me troubleshoot this. I should have tried to replace or look at the house pressure regulator earlier. It would give a consistant pressure across when activating zones, but when I would test other days then it would be a different pressure without me adjusting the pressure regulator. $85 for a new regulator, some elbow grease, and a few minutes and everything works great. I had heard my neighborhood has bad/fluctuating water pressure and believed that instead of checking on the regulator. My fault for not verifying it worked properly.

Is it the diaphragm in your valve? I had a similar problem looked lije low pressure heads would barely pop up if any. Next station everything great. Replaced the top of the inline valve with a new diaphragm. Bingo every thing works fine now. Except one of my other stations atarted to do the same thing within a week. So I am going tobreplace the other 2 as a precaution. I already have them dug up no sense in waiting for thw last one to spit the bit out.